This invention relates to improvements in a flame photometric detector analyzer for continuously analyzing a component in a sample gas, and more particularly to the flame photometric detector analyzer which is suitable for continuously analyzing the concentration of sulfur compounds contained in exhaust gases to measure oil consumption of an internal combustion engine.
It has been proposed to judge the characteristics of an internal combustion engine by measuring engine oil consumption. This engine oil consumption measurement is accomplished by determining the SO.sub.2 concentration in exhaust gases from the engine since sulfur compound is contained in engine oil. Such SO.sub.2 concentration determination is also accomplished by using gas chromatographs, in which the concentration of SO.sub.2 only in a certain amount of a sample gas can be determined, but it is impossible to continuously determine the SO.sub.2 concentration. As appreciated, engine oil consumption varies with varying engine operating conditions, including acceleration, steady state, and deceleration, and with various engine operating parameters such as intake air temperature and engine coolant temperature. In this connection, in order to precisely judge engine characteristics, it is necessary to continuously measure varying oil consumption, i.e., continuously determine the SO.sub.2 concentration in exhaust gases from the engine.
In general, flame photometric detector analyzers are used to continuously measure the concentration of SO.sub.2 in the exhaust gases. In these flame photometric detector analyzers, a fuel gas such as H.sub.2 gas and a combustion supporting gas (usually, atmospheric air containing about 21% O.sub.2) are introduced to a burner or combustion chamber to burn the fuel gas in order to form a flame. Thereafter, a certain amount of sample gas or exhaust gases is introduced into the flame to burn SO.sub.2 in the sample gas, upon which the burnt SO.sub.2 emits flame light. The flame light is then electrically detected by a photomultiplier tube so that the concentration of SO.sub.2 is continuously analyzed.
However, even such flame photometric detector analyzers have encountered the following drawbacks: the abovementioned flame light emitted from the burnt SO.sub.2 is greatly affected with or receives interference effect from various gas components or interference substances such as CO, CO.sub.2, HC (hydrocarbons), O.sub.2 and NO which coexist with SO.sub.2 in the exhaust gases from the engine. In this regard, such flame photometric detector analyzers are effective for analyzing high SO.sub.2 concentration above SO.sub.2 100 ppm, but not effective for analyzing SO.sub.2 concentration in the exhaust gases since the concentration of the exhaust gases is considerably lower.